CN107636060B

CN107636060B - Resin composition for extrusion coating

Info

Publication number: CN107636060B
Application number: CN201680025541.7A
Authority: CN
Inventors: J·王; M·黛米洛斯; D·S·金杰
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2015-05-13
Filing date: 2016-04-26
Publication date: 2021-05-18
Anticipated expiration: 2036-04-26
Also published as: EP3294806B1; MX2017014115A; BR112017023796A2; US20180079897A1; BR112017023796B1; EP3294806A1; CN107636060A; WO2016182727A1; JP2018514632A; ES2864959T3; JP6826997B2; AR104537A1; CO2017011814A2

Abstract

Polyethylene-based compositions are provided that can be used, for example, to form film layers. In one aspect, a composition comprises: (a) a first linear low density polyethylene having a density of 0.900 to 0.915g/cm³And melt index (I)₂)5.0 to 25g/10min, wherein the linear low density polyethylene is a blend of at least two components: (i)20 to 40 weight percent of a second linear low density polyethylene, wherein the second linear low density polyethylene is a polyethylene having a density of 0.870 to 0.895g/cm³And melt index (I)₂)2.0 to 6.0g/10min of a homogeneously branched ethylene/a-olefin interpolymer; and (ii)60 to 80 weight percent of a third linear low density polyethylene, wherein the density of the third linear low density polyethylene is at least 0.02g/cm higher than the density of the second linear low density polyethylene³And wherein the melt index (I) of the third linear low density polyethylene₂) Is the melt index (I) of the second linear low density polyethylene₂) At least twice as large.

Description

Resin composition for extrusion coating

Technical Field

The present invention relates generally to resin compositions, and in some aspects, to extrusion coated resin compositions for providing high hot tack performance.

Background

It is well known that Low Density Polyethylene (LDPE) produced by high pressure polymerisation of ethylene with free radical initiators and homogeneous or heterogeneous Linear Low Density Polyethylene (LLDPE) and Ultra Low Density Polyethylene (ULDPE) produced by copolymerisation of ethylene and alpha-olefins with metallocene or ziegler coordination (transition metal) catalysts at low to medium pressures can be used, for example, for extrusion coating substrates such as paperboard, paper and/or polymeric substrates; for preparing extruded cast films for applications such as disposable diapers and food packaging; and extruded profiles for making, for example, wire and cable jacketing. However, while LDPE generally exhibits excellent extrusion processability and higher extrusion draw rates, LDPE extrusion compositions typically lack sufficient abuse resistance and toughness in many applications. Efforts to improve abuse characteristics by providing LDPE compositions having higher molecular weights (i.e., having a melt index I2 of less than about 2g/10 min) for extrusion coating and extrusion casting purposes are generally not effective because such compositions have too much melt strength to be successfully drawn at higher line speeds.

While LLDPE and ULDPE extrusion compositions provide improved abuse resistance and toughness properties, and MDPE (medium density polyethylene) extrusion compositions provide improved barrier resistance (e.g., resistance to moisture and grease penetration), these linear ethylene polymers typically exhibit unacceptably high levels of shrinkage and tensile instability; the linear ethylene polymers also typically exhibit relatively poor extrusion processability compared to pure LDPE. One solution commonly used in the industry is to blend LDPE with LLDPE. While the addition of LLDPE to LDPE provides some improvement in functionality, additional improvements would still be desirable. One area of interest is improved sealant performance, particularly in terms of hot tack strength of multilayer film structures that may be used, for example, in liquid packaging. While some existing resins provide excellent sealant performance, such resins may be cost prohibitive for some applications or for some thin film converters.

Disclosure of Invention

The present invention utilizes ethylene-based polymers that can provide desirable sealing characteristics (e.g., hot tack strength) when bonded to a film structure. For example, in some embodiments, the resin compositions of the present disclosure provide desirable hot tack strength at relatively low heat seal initiation temperatures and at non-very low densities throughout a broad temperature range.

In one aspect, the present invention provides a composition comprising (a) a first linear low density polyethylene having a density of from 0.900 to 0.915 grams per cubic centimeter (g/cm)³) And melt index (I)₂)5.0 to 25 grams per 10 minutes (g/10min), wherein the linear low density polyethylene is a blend of at least two components: (i)20 to 40 weight percent of a second linear low density polyethylene, wherein the second linear low density polyethylene is a polyethylene having a density of 0.870 to 0.895g/cm³And a homogeneously branched ethylene/alpha-olefin interpolymer having a melt index from 2.0 to 6.0g/10 min; and (ii)60 to 80 weight percent of a third linear low density polyethylene, wherein the density of the third linear low density polyethylene is at least 0.02g/cm higher than the density of the second linear low density polyethylene³And wherein the melt index (I) of the third linear low density polyethylene₂) The melt index (I) of the second linear low density polyethylene₂) At least twice as large.

These examples and other examples are described in more detail in the detailed description.

Drawings

FIG. 1 illustrates the hot tack test results described in the examples.

Detailed Description

Unless otherwise specified, percentages herein are weight percentages (wt%) and temperatures are in units of ° c.

As used herein, the term "composition" includes materials comprising the composition, as well as reaction products and decomposition products formed from the materials of the composition.

The term "comprising" and its derivatives are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is disclosed herein. In order to avoid any doubt, unless stated to the contrary, all compositions claimed herein through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or in other forms. In contrast, the term "consisting essentially of … …" excludes any other components, steps, or procedures from any subsequently recited range, except those that are not essential to operability. The term "consisting of … …" excludes any component, step, or procedure not specifically defined or recited.

As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. Thus, the generic term polymer encompasses the term homopolymer (used to refer to polymers prepared from only one type of monomer, with the understanding that minor amounts of impurities can be incorporated into the polymer structure) and the term interpolymer as defined hereinafter. Minor impurities may be incorporated into and/or within the polymer.

As used herein, the term "interpolymer" refers to a polymer prepared by polymerizing at least two different types of monomers. Thus, the generic term interpolymer encompasses copolymers (which are used to refer to polymers prepared from two different types of monomers), and polymers prepared from more than two different types of monomers. As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. Thus, the generic term polymer encompasses the term "homopolymer", which is generally used to refer to polymers prepared from only one type of monomer; and "copolymer," which refers to a polymer prepared from two or more different monomers.

"polyethylene" shall mean a polymer comprising more than 50% by weight of units that have been derived from ethylene monomers. It comprises a polyethylene homopolymer or copolymer (meaning units derived from two or more comonomers). Common forms of polyethylene known in the art include Low Density Polyethylene (LDPE); linear Low Density Polyethylene (LLDPE); ultra Low Density Polyethylene (ULDPE); very Low Density Polyethylene (VLDPE); single site catalyzed linear low density polyethylene comprising both a linear low density resin and a substantially linear low density resin (m-LLDPE); medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE). These polyethylene materials are generally known in the art; however, the following description may be helpful in understanding the differences between some of these different polyethylene resins.

As used herein, the term "ethylene/a-olefin interpolymer" refers to an interpolymer that comprises, in polymerized form, a majority amount of ethylene monomer (based on the weight of the interpolymer), and at least one a-olefin.

The term "LDPE" may also be referred to as "high pressure ethylene polymer" or "highly branched polyethylene" and is defined to mean that the polymer is partially or completely homopolymerized or copolymerized in autoclave or tubular reactors at pressures above 14,500psi (100MPa) using a free radical initiator (e.g., peroxide) (see, e.g., US 4,599,392, which is incorporated herein by reference). LDPE resins typically have a density in the range of 0.916 to 0.940g/cm 3.

The term "LLDPE" encompasses both resins made using traditional ziegler-natta catalyst systems and single site catalysts such as metallocenes (sometimes referred to as "m-LLDPE"), and encompasses linear, substantially linear, or heterogeneous polyethylene copolymers or homopolymers. LLDPE contains fewer long chain branches than LDPE and includes substantially linear ethylene polymers as further defined in U.S. patent 5,272,236, U.S. patent 5,278,272, U.S. patent 5,582,923, and U.S. patent 5,733,155; homogeneously branched linear ethylene polymer compositions such as those in U.S. Pat. No. 3,645,992; heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Pat. No. 4,076,698; and/or blends thereof (e.g., those disclosed in US 3,914,342 or US 5,854,045). The LLDPE can be made by gas phase, liquid phase or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art, with gas phase and slurry phase reactors being most preferred.

The term "MDPE" means having a density of from 0.926 to 0.940g/cm³The polyethylene of (1). "MDPE" is typically made using a chromium catalyst or a Ziegler-Natta catalyst or using a metallocene, constrained geometry, or single site catalyst, and typically has a molecular weight distribution ("MWD") of greater than 2.5.

The term "HDPE" means a density greater than about 0.940g/cm³Usually prepared with ziegler-natta catalysts, chromium catalysts or even metallocene catalysts.

The composition of the present invention can be provided to be used for eachResins in membrane structures (e.g., thin films, layers in multilayer membrane structures, etc.). For example, the compositions of the present disclosure may provide relatively high hot tack properties when incorporated into a layer of a multilayer film structure without significantly reducing the overall density of the layer. One of the drawbacks in previous attempts to provide resin compositions with higher hot tack is that they require a significant reduction in density. The resin composition of the present invention advantageously will have a very low density and a relatively low melt index (I)₂) Has a relatively small fraction of the linear low density polyethylene and has a relatively high density and a relatively high melt index (I)₂) The linear low density polyethylene composition of (a). The resin compositions of the present invention can have an overall density and an overall melt index that facilitates use of the compositions in extrusion coating applications, extrusion lamination applications, cast film applications, and/or other applications.

As mentioned above, in some embodiments, the present invention provides a composition comprising (a) a first linear low density polyethylene having a density of 0.900 to 0.915 grams per cubic centimeter (g/cm)³) And melt index (I)₂)5.0 to 25 grams per 10 minutes (g/10min), wherein the linear low density polyethylene is a blend of at least two components: (i)20 to 40 weight percent of a second linear low density polyethylene, wherein the second linear low density polyethylene has a density of 0.870 to 0.895g/cm³And a homogeneously branched ethylene/alpha-olefin interpolymer having a melt index from 2.0 to 6.0g/10 min; and (ii)60 to 80 weight percent of a third linear low density polyethylene, wherein the density of the third linear low density polyethylene is at least 0.02g/cm higher than the density of the second linear low density polyethylene³And wherein the melt index (I) of the third linear low density polyethylene₂) The melt index (I) of the second linear low density polyethylene₂) At least twice as large.

The compositions of the invention may comprise a combination of two or more embodiments as described herein.

In some embodiments, the third linear low density polyethylene is a homogeneously branched ethylene/a-olefin interpolymer, while in other embodiments, the third linear low density polyethylene is a heterogeneously branched ethylene/a-olefin polymer.

In one embodiment, the first linear low density polyethylene has a melt index (I)₂)10 to 20g/10 min.

In one embodiment, the second linear low density polyethylene has a density of 0.890g/cm³Or smaller.

In one embodiment, the second linear low density polyethylene has a melt index of 3.0 to 5.0.

In one embodiment, the density of the third linear low density polyethylene is at least 0.024g/cm higher than the density of the second linear low density polyethylene³. In one embodiment, the density of the third linear low density polyethylene is at least 0.026g/cm higher than the density of the second linear low density polyethylene³。

In one embodiment, the composition of the present invention further comprises from 1 to 99 weight percent of a high pressure low density polyethylene.

In one embodiment, the composition of the present invention comprises from 10 to 90 weight percent of the first linear low density polyethylene.

In one embodiment, the composition of the present invention further comprises one or more resin components and the first linear low density polyethylene.

In one embodiment, the composition of the present invention further comprises one or more additives. In various embodiments, the one or more additives are selected from the group consisting of: antioxidants, phosphites, adhesion additives, pigments, colorants, fillers, nucleating agents, clarifying agents, or combinations thereof.

As mentioned above, in some embodiments, the compositions of the present invention are suitable or suitable for use in extrusion coating applications, extrusion lamination applications, cast film applications, and/or other applications.

Some embodiments of the present invention relate to film layers formed from any of the inventive compositions as described herein. Some embodiments of the present invention are directed to films comprising at least one film layer formed from any of the inventive compositions as described herein. Some embodiments of the present invention are directed to articles comprising at least one film layer formed from any of the inventive compositions as described herein.

The composition of the present invention comprises a first Linear Low Density Polyethylene (LLDPE), a second linear low density polyethylene and a third linear low density polyethylene as a blend of at least two components. Preferred blends for making the first linear low density polyethylene used in the compositions of the present invention may be prepared by any suitable means known in the art, including tumble dry blending, gravimetric feeding, solvent blending, melt blending via compound or side arm extrusion, or similar means and combinations thereof.

The first LLDPE may comprise up to 100 wt.% of the composition. As discussed below, in some embodiments, the composition may include a second polyethylene and/or other components. In some embodiments where other components are used, the first LLDPE may comprise at least 10 wt.% of the first LLDPE. All individual values and subranges from 10 to 100 weight percent (wt%) are included herein and disclosed herein; for example, the amount of the first linear low density polyethylene can be from a lower limit of 10, 20, 30, 40, 50, 60, 70, 80, or 90 wt% to an upper limit of 20, 30, 40, 50, 60, 70, 80, 90, or 100 wt%. For example, the amount of the first linear low density polyethylene may be from 10 to 100 wt%, or in the alternative, from 10 to 90 wt%, or in the alternative, from 20 to 80 wt%, or in the alternative, from 30 to 70 wt%.

In some embodiments, the first LLDPE has a density in the range of from 0.900 to 0.915g/cm³Within the range of (1). For example, the density may be from 0.900, 0.902, 0.904, 0.906, 0.908, or 0.910g/cm³To a lower limit of 0.908, 0.910, 0.912, 0.914 or 0.915g/cm³The upper limit of (3).

In one embodiment, the first LLDPE has a melt index (I)₂) From 5.0 to 25g/10 min. In some embodiments, the first LLDPE has a melt index (I)₂) From 10 to 20g/10min, or from 10 to 15 g/10 min. For example, the melt index (I)₂) Can be used forFrom a lower limit of 5.0, 10, 15 or 20 grams/10 minutes to an upper limit of 15, 20 or 25 grams/10 minutes.

In some embodiments, the first LLDPE has a Composition Distribution Branching Index (CDBI) of 50 to 80. In some embodiments, the first LLDPE has a CDBI of 50 to 70.

The first LLDPE can be a physical blend of the dry materials with subsequent melt blending, or the first LLDPE can be made in situ as described and claimed in U.S. patent No. 5,844,045 (the disclosure of which is incorporated herein by reference).

The second LLDPE is the first component of the first LLDPE. The second LLDPE may comprise up to 40 wt.% of the first LLDPE. In some embodiments, the second LLDPE may comprise at least 20 wt.% of the composition. All individual values and subranges from 20 to 40 weight percent are included herein and disclosed herein; for example, the amount of the second linear low density polyethylene can be from a lower limit of 20, 22, 24, 26, 28, or 30 to an upper limit of 30, 32, 34, 36, 38, or 40 wt%. For example, the amount of the second linear low density polyethylene can be from 22 to 38 wt%, or in the alternative, from 26 to 34 wt%.

The second LLDPE is preferably a homogeneously branched ethylene/a-olefin interpolymer. In one embodiment, the alpha-olefin has less than or equal to 20 carbon atoms. For example, the alpha-olefin comonomer may preferably have 3 to 10 carbon atoms, and more preferably 3 to 8 carbon atoms. Exemplary alpha-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. The one or more alpha-olefin comonomers may for example be selected from the group consisting of propylene, 1-butene, 1-hexene and 1-octene; or in the alternative, selected from the group consisting of 1-butene, 1-hexene and 1-octene, and further 1-hexene and 1-octene.

Homogeneous ethylene-based polymers (e.g., ethylene/a-olefin interpolymers) have a uniform distribution of branches, that is, substantially all of the polymer molecules have the same amount of each incorporated comonomer. Composition Distribution Branching Index (CDBI) has been used to characterize branching distribution (or uniformity or non-uniformity) and can be determined according to U.S. patent No. 5,246,783 using the apparatus described in U.S. patent No. 5,008,204, the disclosure of each of which is incorporated herein by reference. The CDBI of the heterogeneous polymer is between 30 and 70, while the CDBI of the homogeneous polymer is between 80 and can be as high as 100.

In some embodiments, the second LLDPE has a density of from 0.870 to 0.895g/cm³Within the range of (1). In some embodiments, the second LLDPE has a density of 0.890g/cm³Or smaller. For example, the density may be from 0.870, 0.875, 0.880, or 0.885g/cm³Lower limit of (2) to 0.890 or 0.895g/cm³The upper limit of (3).

In one embodiment, the second LLDPE has a melt index (I)₂) From 2.0 to 6.0g/10 min. In some embodiments, the second LLDPE has a melt index (I)₂) From 3.0 to 5.0g/10 min. For example, the melt index (I)₂) And may range from a lower limit of 2.0, 2.5, 3.0, or 3.5 grams/10 minutes to an upper limit of 4.5, 5.0, 5.5, or 6.0 grams/10 minutes.

As set forth above, the second LLDPE combines a very low density with a relatively low melt index. Preferably, the second LLDPE has a density of from 0.870 to 0.895g/cm³And melt index (I)₂)2.0 to 6.0g/10min, more preferably, a density of 0.870 to 0.890g/cm3 and a melt index of 3.0 to 5.0g/cm³。

The second component of the first LLDPE is a third LLDPE. The third LLDPE has a higher density and higher melt index than the second LLDPE and is a larger portion of the first LLDPE in weight percent as set forth below.

The third LLDPE may comprise up to 80 wt.% of the first LLDPE. In some embodiments, the third LLDPE may comprise at least 60 wt.% of the first LLDPE. The third LLDPE preferably comprises 60 to 80 wt.% of the first LLDPE. All individual values and subranges from 60 to 80 weight percent (wt%) are included herein and disclosed herein; for example, the amount of the third linear low density polyethylene can be from a lower limit of 60, 62, 64, 66, 68, or 70 to an upper limit of 70, 72, 74, 76, 78, or 80 wt%. For example, the amount of the third linear low density polyethylene can be from 62 to 78 wt%, or in the alternative, from 66 to 74 wt%.

The third LLDPE is an ethylene/α -olefin interpolymer. In one embodiment, the alpha-olefin has less than or equal to 20 carbon atoms. For example, the alpha-olefin comonomer may preferably have 3 to 10 carbon atoms, and more preferably 3 to 8 carbon atoms. Exemplary alpha-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. The one or more alpha-olefin comonomers may for example be selected from the group consisting of propylene, 1-butene, 1-hexene and 1-octene; or in the alternative, selected from the group consisting of 1-butene, 1-hexene and 1-octene, and further 1-hexene and 1-octene.

The third LLDPE may be heterogeneously branched or homogeneously branched, but is preferably homogeneously branched. The homogeneous ethylene-based polymer has a uniform distribution of branches, that is, substantially all of the polymer molecules have the same amount of each incorporated comonomer. Heterogeneously branched ethylene-based polymers (e.g., ethylene/a-olefin interpolymers) are typically produced using ziegler/natta type catalyst systems and have more comonomer distributed in the lower molecular weight molecules of the polymer. Composition Distribution Branching Index (CDBI) has been used to characterize branching distribution (or uniformity or non-uniformity) and can be determined according to U.S. patent No. 5,246,783 using the apparatus described in U.S. patent No. 5,008,204, the disclosure of each of which is incorporated herein by reference. The CDBI of the heterogeneous polymer is between 30 and 70, while the CDBI of the homogeneous polymer is between 80 and can be as high as 100.

In some embodiments, the density of the third LLDPE is at least 0.02g/cm higher than the density of the second LLDPE³. In some embodiments, the density of the third LLDPE is at least 0.024g/cm higher than the density of the second LLDPE³. In some embodiments, the density of the third LLDPE is at least 0.026g/cm higher than the density of the second LLDPE³. In some embodiments, the third LLDPE has a density of from 0.900 to 0.930g/cm³Within the range of (1). In some embodiments, the third LLDPE has a density of 0.890g/cm³Or greater, preferably 0.900g/cm³Or greater, more preferably 0.910g/cm³Or larger. In some embodiments, the third LLDPE has a density of from 0.910 to 0.920g/cm³Within the range of (1). For example, the density may be from 0.900, 0.905, 0.910, 0.915 or 0.920g/cm³To a lower limit of 0.910, 0.915, 0.920, 0.925 or 0.930g/cm³The upper limit of (3).

In some embodiments, the third LLDPE has a melt index (I)₂) At least twice the melt index of the second LLDPE. In some embodiments, the third LLDPE has a melt index (I)₂) At least three times the melt index of the second LLDPE. In some embodiments, the third LLDPE has a melt index (I)₂) At least four times the melt index of the second LLDPE. In some embodiments, the third LLDPE has a melt index (I)₂) From 10 to 30 g/10 min. In some embodiments, the third LLDPE has a melt index (I)₂) From 15 to 25g/10 min. For example, the melt index (I)₂) And may range from a lower limit of 10, 12.5, 15, 17.5, 20, 22.5, or 25 grams/10 minutes to an upper limit of 20, 22.5, 25, 27.5, or 30 grams/10 minutes.

As set forth above, the third LLDPE will be at least 0.020g/cm higher than the second LLDPE³Density of (D) and melt index (I) of the second LLDPE₂) Melt index (I)₂) And (4) combining.

In some embodiments, the first LLDPE may comprise other components.

In some embodiments, the compositions of the present invention may include other components in addition to the first LLDPE. In some embodiments, the compositions of the present disclosure may further comprise a second polyethylene resin, such as another ethylene/a-olefin interpolymer. For example, in some embodiments, the compositions of the present disclosure may include LDPE (i.e., high pressure low density polyethylene). The LDPE may comprise from 1 to 99 wt% of the total composition, alternatively from 3 to 50 wt% of the total composition, alternatively from 10 to 40%, more preferably from 15 to 35%. In general, the more LDPE resin that may be included, the less first LLDPE may be needed to obtain good neck-in characteristics. Such LDPE materials are in the artAre well known and comprise resins made in autoclave or tubular reactors. Preferred LDPE's for use as the second polyethylene resin have a density of from 0.915 to 0.930g/cm³Preferably from 0.916 to 0.925g/cm³More preferably from 0.917 to 0.920g/cm³Within the range of (1).

Such as antioxidants (e.g., hindered phenols, such as supplied by Ciba Geigy)

1010 or

1076) Phosphites (e.g. also provided by Ciba Geigy)

168) Adhesion additives (e.g., PIB), Standostab PEPQ^TMAdditives (provided by Sandoz), pigments, colorants, fillers, nucleating agents, clarifying agents, and the like may also be included in the compositions of the present invention to the extent that they do not substantially interfere with the performance of the compositions (e.g., in extrusion coating applications, extrusion lamination applications, and/or cast film applications). These compositions preferably contain no or only limited amounts of antioxidants, as these compounds may interfere with adhesion to the substrate in some applications. The compositions of the present invention or articles made using the compositions of the present invention may also contain additives to enhance antiblock and coefficient of friction properties, including but not limited to untreated and treated silica, talc, calcium carbonate, and clay, as well as primary, secondary, and substituted fatty acid amides, chill roll release agents, silicone coatings, and the like. Other additives may also be added to enhance the anti-fog properties of, for example, transparent cast films, as described by Niemann, for example, in U.S. patent No. 4,486,552, the disclosure of which is incorporated herein by reference. Still other additives, such as quaternary ammonium compounds alone or in combination with Ethylene Acrylic Acid (EAA) copolymers or other functional polymers, may also be added to enhance the coatings of the present inventionAntistatic properties of cloth, profiles and films, and allow, for example, packaging or manufacturing of electronically sensitive goods. Other functional polymers such as maleic anhydride grafted polyethylene may also be added to enhance adhesion, especially to polar substrates.

Preferred blends for making the polymeric extrusion compositions of the present invention can be prepared by any suitable means known in the art, including tumble dry blending, gravimetric feeding, solvent blending, melt blending via compound or side arm extrusion, or similar means and combinations thereof.

The compositions of the present invention, whether used in monolayer or multilayer constructions, can be used to make extrusion coated, extruded profiles, and extrusion cast films as are generally known in the art. When the present compositions are used for coating purposes or in multilayer constructions, the substrate or adjacent material layers may be polar or non-polar, including for example (but not limited to) paper products, metals, ceramics, glass, and various polymers (especially other polyolefins), and combinations thereof. For extrusion distribution, a variety of articles can potentially be manufactured, including but not limited to refrigerator gaskets, wire and cable jacketing, wire coating, medical tubing and water piping, where the physical properties of the composition are suitable for the purpose. Extruded cast films made from or with the compositions of the present invention can also potentially be used in food packaging and industrial wrap film applications.

Unless otherwise indicated herein, the following analytical methods are used to describe aspects of the invention:

melt index

Melt index I was measured according to ASTM D-1238 at 190 ℃ and under loads of 2.16kg and 10kg, respectively₂(or I2) and I₁₀(or I10). The values are reported in g/10 min.

Density of

Samples for density measurement were prepared according to ASTM D4703. Measurements were made within one hour of sample pressing according to ASTM D792, method B.

Dynamic shear rheology

Each sample was compression molded into a "3 mm thick by 25mm diameter" circular sheet at 177 ℃ under a pressure of 10MPa in air for 5 minutes. The samples were then removed from the press and placed on a counter to cool.

Constant temperature frequency sweep measurements were performed on an ARES strain controlled rheometer (TA instrument) equipped with 25mm parallel plates under a nitrogen purge. For each measurement, the rheometer was allowed to thermally equilibrate for at least 30 minutes before the gap was zeroed. The sample discs were placed on a plate and allowed to melt at 190 ℃ for five minutes. The plate was then brought close to 2mm, the sample trimmed, and the test was then started. The process was additionally set up with a five minute delay to allow for temperature equilibration. The experiment was performed at five points every ten over a frequency range of 0.1 to 100rad/s at 190 ℃. The strain amplitude was constant at 10%. The pressure response is analyzed in terms of amplitude and phase, from which the storage modulus (G '), loss modulus (G "), complex modulus (G'), dynamic viscosity (η ·oreta ·), and tan δ (or tan delta) are calculated.

DSC

Differential Scanning Calorimetry (DSC) was measured by a TA Q1000DSC (TA instruments; New Castle, DE) equipped with an RCS (refrigeration cooling system) cooling accessory, and tested using an autosampler module. During the test, a nitrogen purge gas flow rate of 50ml/min was used. Each sample was pressed into a film and melted in a press at about 175 ℃; the molten sample was then allowed to air cool to room temperature (-25 ℃). A 3 to 10mg sample of the cooled material was cut into 6mm diameter disks, weighed, placed in a lightweight aluminum pan (approximately 50mg), and crimped closed. The samples were then tested for thermal behavior.

The thermal behavior of the sample is determined by varying the sample temperature up and down to form a response curve to temperature. The sample was first rapidly heated to 180 ℃ and held isothermally for 3 minutes to remove any previous thermal history. Subsequently, the sample was then cooled to-40 ℃ at a cooling rate of 10 ℃/min and held at-40 ℃ for 3 minutes. The sample was then heated to 150 ℃ at a heating rate of 10 ℃/minute. The cooling curve and the second heating curve were recorded. The measured value is the peak melting temperature (T)_m) Peak crystallizationTemperature (T)_c) Heat of fusion (H)_f). Reporting heat of fusion (H) from second heating curve_f) And peak melting temperature. The peak crystallization temperature was determined from the cooling curve.

Conventional gel permeation chromatography (conv. GPC)

A GPC-IR high temperature chromatography system from pelimo corporation (PolymerChar, Valencia, Spain) was equipped with a precision detector (Amherst, MA), a model 2040 2-angle laser light scattering detector, an IR5 infrared detector, and a 4-capillary viscometer (both from pelimo). Data acquisition was performed using Perry Moire Instrument control software and a data acquisition interface. The system was equipped with an online solvent degasser and pumping system from Agilent Technologies, Santa Clara, CA.

The injection temperature was controlled at 150 degrees celsius. The columns used were three 10 micron "hybrid B" columns from Polymer Laboratories (Shropshire, UK). The solvent used was 1,2,4 trichlorobenzene. Samples were prepared at a concentration of "0.1 g polymer in 50ml solvent". The chromatographic solvent and the sample preparation solvent each contained "200 ppm of Butylated Hydroxytoluene (BHT)". Both solvent sources were sparged with nitrogen. The ethylene-based polymer sample was gently stirred at 160 degrees celsius for three hours. The injection volume was 200 microliters and the flow rate was 1 milliliter/minute. The GPC column set was calibrated by running 21 "narrow molecular weight distribution" polystyrene standards. The Molecular Weight (MW) of the standard is in the range of 580 to 8,400,000 g/mole, and the standard is contained in a six "cocktail" mixture. Each standard mixture has at least a tenfold separation between individual molecular weights. The standard mixture was purchased from polymer laboratories. Polystyrene standards are prepared at 0.025g in 50mL of solvent for molecular weights equal to or greater than 1,000,000 g/mole and 0.050g in 50mL of solvent for molecular weights less than 1,000,000 g/mole.

The polystyrene standards were dissolved at 80 ℃ for 30 minutes with gentle agitation. The narrow standard mixture was run first and degradation was minimized in the descending order of "highest molecular weight component". The peak polystyrene standard molecular weight was converted to polyethylene molecular weight using equation 1 (as described in Williams and Ward, journal of polymer science: journal of polymer press (j.polym.sci., polym.letters), 6,621, (1968):

M_polyethylene＝A×(M_Polystyrene)^B(equation 1) of the reaction mixture,

where M is the molecular weight, A equals 0.4316 and B equals 1.0.

The number average molecular weight (mn (conv gpc)), the weight average molecular weight (Mw-conv gpc), and the z average molecular weight (mz (conv gpc)) were calculated according to the following equations 2 to 4:

in equations 2 through 4, RV is the column retention volume (linear interval), collected at "1 point per second", IR is the baseline-subtracted IR detector signal from the IR5 measurement channel of the GPC instrument, in volts, and LogM_PEIs the polyethylene equivalent MW determined from equation 1. Data calculations were performed using "GPC One software (version 2.013H)" from pely mordane.

Crystallization Elution Fractionation (CEF)

Fractionation (CEF) by crystallization elution with a model 2040 two-angle light scattering detector (precision detector, currently Agilent Technologies) equipped with an IR-4 detector (Perimex, Spain) and a Perimex (Perimex, Spain) Monrabal et al, Macro. symposium (Macromol. Symp.) -257, 71-79 (2. RTM. Symp.) (Perimex, Inc.)007) Analysis of comonomer distribution was performed. The IR-4 detector operates in the constituent mode with two filters, C006 and B057. A50X 4.6mm 10 micron guard column (Polymer laboratories, now Agilent technologies) was installed just before the IR-4 detector in the detector oven. Ortho-dichlorobenzene (ODCB, 99% anhydrous grade) and 2, 5-di-tert-butyl-4-methylphenol (BHT) were purchased from Sigma-Aldrich. Silica gel 40 (particle size 0.2-0.5 mm) was purchased from EMD Chemicals. The silica gel was dried in a vacuum oven at 160 ℃ for about two hours before use. Eight hundred milligrams of BHT and five grams of silica gel were added to two liters of ODCB. ODCB containing BHT and silica gel is now referred to as "ODCB". The ODBC was treated with dry nitrogen (N) prior to use₂) Bubbling for one hour. The dried nitrogen is passed through<90psig conveying nitrogen through CaCO₃And

molecular sieves to obtain such nitrogen. The resulting nitrogen should have a dew point of approximately-73 ℃. Sample preparation was performed at 160 ℃ for 2 hours with shaking using an autosampler at 4mg/ml (unless otherwise specified). The injection volume was 300 ml. The temperature profile of the CEF is: crystallizing at from 110 ℃ to 30 ℃ at 3 ℃/min; heat equilibration at 30 ℃ for 5 minutes (including soluble fraction elution time set to 2 minutes); eluting at 3 deg.C/min from 30 deg.C to 140 deg.C. The flow rate during crystallization was 0.052 ml/min. The flow rate during elution was 0.50 ml/min. Data was collected at one data point/second.

The CEF column was packed according to US 2011/0015346A 1 by the Dow Chemical Company using 125 μm + -6% glass beads (MO-SCI specialty products) with 1/8 inch stainless steel tubing. The internal liquid volume of the CEF column is between 2.1mL and 2.3 mL. Column temperature calibration was performed by using a mixture of NIST standard reference materials linear polyethylene 1475a (1.0mg/ml) and eicosane (2mg/ml) in ODCB. CEF temperature calibration consists of four steps:⁽¹⁾calculating a delay volume defined as the measured eicosane peak elution temperature minus a temperature shift between 30.00 ℃;⁽²⁾the temperature offset of the elution temperature was subtracted from the CEF raw temperature data. It should be noted that it is possible to note,this temperature shift is a function of experimental conditions, such as elution temperature, elution flow rate, and the like;⁽³⁾creating a linear calibration line converting elution temperatures in the range of 30.00 ℃ and 140.00 ℃ such that NIST linear polyethylene 1475a has a peak temperature at 101.0 ℃ and eicosane has a peak temperature of 30.0 ℃;⁽⁴⁾for the soluble fraction measured isothermally at 30 ℃, the elution temperature was linearly extrapolated by using an elution heating rate of 3 ℃/min. The reported elution peak temperatures were obtained so that the observed comonomer content calibration curves were consistent with those previously reported in US 2011/0015346 a 1. The data from this analysis is used to calculate the CDBI as set forth herein.

Hot tack property

Hot tack measurements on the films were made using an Enepay commercial test machine, according to ASTM F-1921 (method B). Prior to testing, the samples were conditioned at 23 ℃ and 50% r.h. for a minimum of 40 hours following astm d-618 (procedure a). The hot tack test simulates filling the material into a pouch or bag before the seal is likely to cool completely.

An 8.5 "x 14" size sheet was cut in the machine direction from the three layer coextruded laminated film having the longest dimension. Strips 1 "wide and 14" long were cut from the film [ the sample need only be of sufficient length to be gripped ]. These samples were tested over a range of temperatures and the results reported as the maximum load as a function of temperature. Typical temperature steps are 5 ℃ or 10 ℃, with 6 replicates at each temperature. The parameters used in the test were as follows:

sample width: 25.4mm (1.0in)

Sealing pressure: 0.275N/mm²

Sealing residence time: 1.0s

Delay time: 0.18s

Stripping speed: 200mm/s

The endepay machine produced a 0.5 inch seal. The data is reported as a hot tack curve, where the average hot tack force (N) is plotted as a function of temperature, as shown, for example, in fig. 1. The hot tack initiation temperature is the temperature required to achieve a predefined minimum hot tack force. This force is typically in the range of 1N to 2N, but will vary depending on the particular application. The final hot tack strength is the peak in the hot tack curve. The hot tack range is the temperature range at which the seal strength exceeds the minimum hot tack force.

Comonomer Distribution Branching Index (CDBI)

The CDBI was determined according to U.S. patent No. 5,246,783 using the apparatus described in U.S. patent No. 5,008,204, depending on the data from the Crystallization Elution Fractionation (CEF) analysis set forth above, the disclosure of each of which is incorporated herein by reference.

Examples of the invention

The following examples illustrate the invention but are not intended to limit the scope of the invention.

Preparation of blend Components and comparative composition A

Blend component a and blend component B for use in the compositions of the present invention and comparative composition a were prepared as follows. All raw materials (monomers and comonomers) and process solvents (narrow boiling range high purity isoparaffinic solvents) are purified with molecular sieves prior to introduction into the reaction environment. Hydrogen was supplied in pressurized cylinders at high purity levels and was not further purified. The reactor monomer feed stream is pressurized to greater than the reaction pressure by a mechanical compressor. The solvent and comonomer feeds are pressurized by pumps to above the reaction pressure. The individual catalyst components were manually batch diluted with purified solvent to the specified component concentrations and pressurized above the reaction pressure. All reaction feed flows were measured with mass flow meters and independently controlled with a computer automated valve control system.

Fresh comonomer feed is mechanically pressurized and can be injected into the process at several potential locations depending on the reactor configuration, the comonomer feed comprising: a feed stream for only the first reactor, a feed stream for only the second reactor, and two separate first and second reactor feed streams; or injected into a common stream before the solvent is split into the two reactors. Some comonomer injection combinations are only possible when running a dual reactor configuration.

The reactor configuration options included single reactor operation (for blend component a and blend component B) and dual series reactor operation (for comparative composition a).

The continuous solution polymerization reactor consists of a liquid-filled non-adiabatic isothermal circulating loop reactor, which simulates a Continuously Stirred Tank Reactor (CSTR) under heat removal. It is possible to control all fresh solvent, monomer, comonomer, hydrogen and catalyst component feeds independently. Temperature control of all fresh feed streams (solvent, monomer, comonomer and hydrogen) to the reactor was performed by passing the feed streams through a heat exchanger. All fresh feed to the polymerization reactor was injected into the reactor at two locations, with approximately equal reactor volumes between each injection location. Fresh feed was controlled with each injector receiving half of the total fresh feed mass flow. The catalyst components are injected into the polymerization reactor via specially designed injection stingers and combined into a mixed catalyst/cocatalyst feedstream prior to injection into the reactor. The main catalyst component feed was computer controlled to maintain the reactor monomer conversion at the specified target. The co-catalyst component is fed based on the calculated specified molar ratio to the main catalyst component. Immediately after each fresh injection site (feed or catalyst), the feed stream was mixed with the circulating polymerization reactor contents using static mixing elements. The contents of the reactor are continuously circulated through a heat exchanger which is responsible for removing much of the heat of reaction and the temperature of the coolant side is responsible for maintaining the isothermal reaction environment at the specified temperature. Circulation around the reactor loop is provided by a pump.

In a dual series reactor configuration (for comparative composition a), the effluent from the first polymerization reactor (containing solvent, monomer, comonomer, hydrogen, catalyst components, and polymer) exits the first reactor loop and is added into the second reactor loop downstream of the second reactor low pressure fresh feed injection.

In all reactor configurations, the final reactor effluent (the second reactor effluent of a dual series reactor or a single reactor effluent) enters a zone that is deactivated with the addition and reaction of a suitable reactant, typically water. Other additives may also be added at this same reactor exit point.

After catalyst deactivation and addition of additives, the reactor effluent enters a devolatilization system where polymer is removed from the non-polymer stream. The separated polymer melt was pelletized and collected. The non-polymer stream passes through various parts of the equipment that separate most of the ethylene removed from the system. Most of the solvent and unreacted comonomer are recycled back to the reactor after passing through the purification system. Small amounts of solvent and comonomer are purged from the process.

The polymerization conditions for blend components a and B are reported in table 1. The first reactor catalyst (CatA) was (tert-butyl (dimethyl (3- (pyrrolidin-1-yl) -1H-inden-1-yl) silyl) amino) dimethyl titanium. The first reactor co-catalyst (CatB) was bis (hydrogenated tallow alkyl) methyl, tetrakis (pentafluorophenyl) borate (1-) amine. The first reactor scavenger (CatC) is Modified Methylaluminoxane (MMAO).

TABLE 1

The polymerization conditions for comparative composition a made in a dual series reactor configuration are reported in table 2. The first reactor catalyst (CatD) is [ N- (1, 1-dimethylethyl) -1, 1-dimethyl-1- [ (1,2,3,4,5-. eta.) -2,3,4, 5-tetramethyl-2, 4-cyclopentadien-1-yl group]Silaneamino (2-) -. kappa.N][ (1,2,3,4-. eta.) -1, 3-pentadiene]-titanium. The first reactor co-catalyst (CatE) was tris (2,3,4,5, 6-pentafluorophenyl) borane. The first reactor scavenger (CatC) is Modified Methylaluminoxane (MMAO). The second reactor catalyst is a ziegler-natta premix. The second reactor cocatalyst (CatF) was Triethylaluminium (TEA). Comparative composition A included 58% of the first reactor component, which was melt index I₂15 g/10min and a density of 0.9016g/cm³A homogeneously branched LLDPE component of (a); and 42% of the second reactionA container component having a melt index of 15 g/10min and a density of 0.9219g/cm³The heterogeneously branched LLDPE component of (a).

TABLE 2

Various properties of blend components a and B were measured and reported in table 3. Blend components a and B are homogeneously branched LLDPE useful in forming the inventive compositions of the present invention. Blend component C is available from the Dow chemical company as DOWLEX^TM2517, and its properties were also measured and reported in table 2. Blend component C may be used with blend component a to also form the inventive composition of the present invention.

TABLE 3

	Unit of	Blend component A	Blend component B	Blend component C
					Type (B)		Uniformity	Uniformity	Non-uniformity
Density of	g/cc	0.887	0.916	0.917
					I₂	g/10min	4.3	21.6	25.6
I₁₀/I₂		6.1	6.1	6.9
					Mn(conv.)	g/mol	36,968	21,390	15,713
Mw(conv.)	g/mol	76,919	48,121	50,639
					Mz(conv.)	g/mol	125,250	80,015	127,379
Mw/Mn		2.08	2.25	3.22
					Mz/Mw		1.63	1.66	2.52
Eta*(0.1rad/s)	Pa.s	1,518	329	403
					Eta*(1.0rad/s)	Pa.s	1,496	328	395
Eta*(10rad/s)	Pa.s	1,330	317	353
					Eta*(100rad/s)	Pa.s	835	252	250
Eta0.1/Eta100		1.82	1.30	1.61
					Tm1	℃	82.6	108.9	123.9
Tm2	℃			117.3
					Tm3	℃			107.2
Tc1	℃	63.4	91.3	103.4
					CDBI		99.4	82.9	54.6

Preparation of inventive compositions

Inventive compositions 1 and 2 were prepared from blend components A, B and C. Inventive composition 1 was manufactured using 30% blend component a and 70% blend component B. Inventive composition 2 was manufactured using 30% blend component a and 70% blend component C. Various properties of inventive compositions 1 and 2 and comparative composition a compositions were measured and reported in table 4.

TABLE 4

Preparation of coextruded cast films

The 3-layer coextruded cast film was prepared from Collin cast film wire. The casting line consisted of two 20mm and one 30mm 25:1L/D dr collin extruders having an air cooled barrel and a water cooled inlet feed zone. All extruders had specially-molded resistant (Xaloy)/nocin (Nordson) barrier type screws. The barrel, the inside of the die and the feed block are all coated with a corrosion resistant coating. The control system consists of proprietary FECON dr. The extrusion process was monitored by a pressure sensor positioned before the breaker plate and four heater zones on a 30mm barrel and three heater zones on a 20mm barrel (each zone located at the adapter, two on the feed block, and two zones on the die). The software also tracks extruder RPM, amp, kg/hr rate, melt pressure (barrier), line speed, and melt temperature for each extruder.

The equipment specifications contained a dr. collin three/five layer feed block and a dr. collin 250mm curved lip casting mold. Three chill rolls had a polished chrome finish, with primary coils 144mm o.d. × 350mm long, and two additional chill rolls 72mm o.d. × 350mm long. The surface of these rolls was trimmed to 5 to 6 μm. All three cooling rolls have cooling water circulated through them to provide quenching, with a temperature control unit added to control the GWK TECO microprocessor for heating the rolls up to 90 ℃. The rate was measured by three inosex weighing hoppers, with a force-counting sensor on each hopper for gravity control. The film or foil roll was wound on a dr.collin two position winder on a 3"i.d. core. The output film and sheet slitter table is positioned in front of the rolls with the adjusters collected under the table on two tension adjustable spools. The maximum throughput rate of the line was 12kg/hr (using three extruders) and the maximum line speed was 65 m/min.

The cast film consisted of 3 layers with a total film thickness of 3.5 mils. The three layers are in the ratio of 25% sealant layer, 50% tie layer and 25% backing layer. The sealant layer was formed from 100% of inventive composition 1, inventive composition 2, or comparative composition a. Inventive compositions 1 and 2 were formed by weighing the blend components (as indicated in tables 2 and 3 above) and then tumble blended for at least 30 minutes before supplying them to the extruder to form the sealant layer. The tie layer comprises 90% ATTANE^TM4202 ULLDPE and 10% AMPLIFY GR 205 functional polymer blends, both of which are commercial resins supplied by the Dow chemical company. The two components were weighed and then tumble blended for at least 30 minutes before being fed into an extruder to form a bonding layer. The backing layer comprises Ultramid Nylon B36 LN supplied by BASF.

The hot tack of each of the films was measured as described above, and the results are shown in fig. 1. As shown in fig. 1, inventive compositions 1 and 2 each exhibited substantially higher hot tack strength over a wider temperature range than comparative composition a. Inventive compositions 1 and 2 also exhibit significantly reduced heat seal initiation temperatures relative to comparative composition a.

Claims

1. A composition for a sealant layer of a film, comprising:

(a) a first linear low density polyethylene having a density of from 0.900 to 0.915g/cm³And melt index I₂From 5.0 to 25g/10min, wherein the linear low density polyethylene is a blend of at least two components:

(i)26 to 34 weight percent of a second linear low density polyethylene, wherein the second linear low density polyethylene is a polyethylene having a density of 0.875 to 0.895g/cm³And melt index I₂2.0 to 6.0g/10min of a homogeneously branched ethylene/1-octene interpolymer; and

(ii)66 to 74 weight percent of a third linear low density polyethylene, wherein the third linear low density polyethylene has a density of 0.900 to 0.925g/cm³And the density of the third linear low density polyethylene is at least 0.02g/cm higher than the density of the second linear low density polyethylene³And wherein the melt index I of the third linear low density polyethylene₂Is the melt index I of the second linear low density polyethylene₂At least two times, wherein the third linear low density polyethylene is an ethylene/1-octene interpolymer.

2. The composition of claim 1, wherein the third linear low density polyethylene is a homogeneously branched ethylene/1-octene interpolymer.

3. The composition of claim 1, wherein the third linear low density polyethylene is a heterogeneously branched ethylene/1-octene interpolymer.

4. The composition of any of the preceding claims, wherein the first linear low density polyethylene has a melt index of from 10 to 20 grams per 10 minutes.

5. The composition of any of claims 1-3, wherein the second linear low density polyethylene has a density of from 0.875 to 0.890g/cm³。

6. The composition of any one of claims 1-3, wherein the second linear low density polyethylene has a melt index of from 3.0 to 5.0g/10 min.

7. The composition of any of claims 1-3, wherein the density of the third linear low density polyethylene is at least 0.024g/cm higher than the density of the second linear low density polyethylene³。

8. The composition of any of claims 1-3, wherein the composition further comprises from 1 to 99 weight percent of a high pressure low density polyethylene.

9. A film comprising at least one layer made from the composition of any one of the preceding claims.

10. An article comprising at least one film according to claim 9.